Listening Technology for Wheelsets for Safer Trains

This solution improves the reliability of rail transport and reduces maintenance costs. As reported in the current issue of Pictures of the Future, the system registers the running sounds of wheelset bearings in trains that are under way.

For more than two years, RailBAM has been monitoring 45 trains with a total of 9,000 wheelsets in Southampton, UK. Normally, wheelsets are replaced every 1.2 million kilometers. Because RailBAM can detect damage long before an actual failure occurs, technicians can now replace wheelsets whenever the measurement data shows the first changes.

As a result, it has been possible to extend the maintenance intervals for powered and non-powered wheelsets by ten and 50 percent, respectively. RailBAM was developed by Track IQ, a Siemens partner, and is marketed exclusively by Siemens.

Wheelsets experience more operational stress than any other train component. Wind and weather, high speeds and vibration make them susceptible to wear and contamination from dirt. At the same time, damage to a wheelset is a serious risk to safety, because if a wheel fails it is likely that the train will derail. Wheelsets are therefore regularly subject to visual inspection and ultrasound examination and after a set number of kilometers they are replaced.

RailBAM now makes it possible to regularly monitor the wheelset bearings of trains in service. The system is based on an acoustic sensor that is mounted along the rails and continuously records the running sounds of all trains. At the depot, measurement data is collected and assigned to a specific train based on the railroad's timetable. Software extracts the measurement values for the wheelsets from the acoustical data and compares them to reference values.

Early stages of damage to bearings cause characteristic changes in the running sounds of the wheels. If such alterations appear, the effected wheelset will be replaced the next time the train returns to a depot. In this way, sudden failure can be prevented. Conversely, a wheelset is allowed to remain in service beyond its normal maintenance interval, as long as the monitoring data doesn't show any problems that require attention.

At the moment, RailBAM can be used to monitor trains traveling at speeds up to a maximum of 160 kilometer per hour. However, due to the high level of interest from various rail operators, there are plans to adapt the system so that it can also operate with high-speed trains.